LOCATION MONOWI                  NE

Established Series
Rev. OI-JRC-AJO
11/2022

MONOWI SERIES

The Monowi series consists of moderately deep, well drained slow or very slowly permeable soils formed in clay residuum weathered from calcareous and gypsiferous shale. These upland soils have slopes ranging from 2 to 30 percent. Mean annual temperature is about 9 degrees C, and mean annual precipitation is about 559 millimeters.

TAXONOMIC CLASS: Fine, smectitic, mesic Typic Haplustepts

TYPICAL PEDON: Monowi silty clay - on an 8 percent convex west-facing slope in a cultivated field. When described the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)

Ap--0 to 10 centimeters; dark grayish brown (10YR 4/2) silty clay, dark grayish brown (10YR 4/2) moist; weak fine granular structure; slightly hard friable; many fine and medium roots; strong effervescence; moderately alkaline; abrupt smooth boundary. (8 to 15 centimeters thick)

A--10 to 20 centimeters; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; weak coarse subangular blocky structure parting to weak medium and fine subangular; hard, firm; many very fine and few fine roots; strong effervescence; moderately alkaline; abrupt wavy boundary. (0 to 20 centimeters thick)

BA--20 to 36 centimeters; light olive brown (2.5Y 5/4) silty clay, olive brown (2.5Y 4/4) moist; weak coarse subangular blocky structure parting to moderate medium and fine angular blocky; hard, firm; few fine and medium roots; strong effervescence; moderately alkaline; gradual smooth boundary. (0 to 15 centimeters thick)

Bw--36 to 71 centimeters; light yellowish brown to light olive brown (2.5Y 5/4) clay; olive brown (2.5Y 4/4) moist; weak coarse prismatic structure parting to moderate fine angular blocky; very hard, very firm; few fine roots; strong effervescence; moderately alkaline; smooth boundary. (15 to 38 centimeters thick)

C--71 to 84 centimeters; light yellowish brown (2.5Y 6/4) clay; light olive brown (2.5Y 5/4) moist; massive; hard, firm; few very fine roots moving between parallel shale plates; many fine shale fragments; common carbonate masses and gypsum crystals interspersed with clay; strong effervescence; moderately alkaline; gradual smooth boundary. (8 to 38 centimeters thick)

Cr--84 to 200 centimeters; pale yellow (2.5Y 7/4) bedded shale; light olive brown (2.5Y 5/4) moist; massive breaking to moderate medium and coarse platy fragments; hard, firm; few very fine roots between parallel shale plates; many carbonate masses and gypsum and carbonate crystals in seams; strong effervescence; moderately alkaline.
TYPE LOCATION: Boyd County, Nebraska; about 1/2 mile south of Bristow; 2112 feet north, 200 feet east of the southwest corner, sec. 14, T. 33 N., R. 11 W.

RANGE IN CHARACTERISTICS: Typically, free calcium carbonate is present in the profile, and the depth to soft, partially weathered shale is 50 to 100 centimeters. In addition to the carbonate masses, the parent material and shale contains 30 to 40 percent gypsum in seams and pockets. It is slightly alkaline to strongly alkaline.

Particle-size control section (weighted average):
Clay content: 35 to 59 percent
Sand content: 2 to 10 percent

Ap and A horizons:
Hue: 10YR or 2.5Y
Value: 4 to 6 dry, 2 to 4 moist
Chroma: 2 or 3 dry or moist
Texture: silty clay or silty clay loam
Clay content: 28 to 50 percent
Reaction: slightly alkaline or moderately alkaline

Bw horizon:
Hue: 10YR or 2.5Y
Value: 4 to 7 dry, 3 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: silty clay or clay
Clay content: 35 to 59 percent
Reaction: moderately alkaline or strongly alkaline
Sometimes BA horizons are present.


C horizon:
Hue: 2.5 Y or 5Y
Value: 6 to 8 dry, 4 to 6 moist
Chroma: 2 to 6 dry or moist
Texture: silty clay or silty clay loam
Clay content: 24 to 59 percent
Reaction: slightly alkaline to strongly alkaline

Cr horizon:
Hue: 2.5 Y or 5Y
Value: 6 to 8 dry, 4 to 6 moist
Chroma: 1 to 4 dry or moist
Texture: weathered bedrock
Clay content: 24 to 59 percent
Reaction: slightly alkaline to strongly alkaline

COMPETING SERIES: Monowi is the only series in this family.

GEOGRAPHIC SETTING: The Monowi soils are on gently sloping to steep uplands. Slopes range from 2 to 30 percent. They formed in clay residuum weathered from calcareous and gypsiferous, light colored, soft shales. The average annual precipitation ranges from about 500 to 600 millimeters. The average annual air temperature ranges from about 8 to 10 degrees C.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boyd, Bristow, Lakoma, Sansarc, and Verdelsoils. Boyd and Lakoma soils have developed in dark shales and occur above Monowi soils. Bristow and Sansarc soils are less than 50 centimeters to bedrock and occur above Monowi. Verdel soils have vertic characteristics and are on terrace positions.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; surface runoff is medium on the 3 to 7 percent slopes, and rapid on slopes greater than 7 percent. Saturated hydraulic conductivity is slow or very slow. After dry periods, cracks make initial intake rapid.

USE AND VEGETATION: Cropland and rangeland. The less sloping areas are mostly in cropland; small grains, sorghum, and alfalfa are the principal crops. The more sloping areas are in native range; the vegetation consists of mid and tall grasses.

DISTRIBUTION AND EXTENT: North-central Nebraska and south-central South Dakota. These soils are of moderate extent, and are confined to light colored shale outcrop areas along the Missouri River and its tributaries.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Salina, Kansas.

SERIES ESTABLISHED: Boyd County, Nebraska, 1976.

REMARKS: Laboratory sample numbers 77P0220-77P0225.

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National Cooperative Soil Survey
U.S.A.